This invention relates to apparatus for recognition of ventricular tachycardia and ventricular fibrillation from epicardial electrogram timings, and for termination thereof.
Ventricular fibrillation is defined as a condition characterized by fibrillary electrical activity of the ventricular muscle, the electrical impulses traversing the ventricles so rapidly that coordinated contractions cannot occur. This must be distinguished from ventricular tachycardia which may be defined as a rapid (greater than 100 beats per min.) cardiac rhythm originating in the ventricles. If sustained, it is usually synchronized in terms of overall ventricular contraction. Both should be differentiated from the normal situation of sinus rhythm where the heart's rhythm is controlled by depolarization originating from the sinus node and which spread sequentially through the atria, the AV node, the His-Purkinje system, and ventricular myocardium.